How to test older amp before use?

bansheesho

What are the proper steps for checking an older amp (say adcom gfa 555) before hooking speakers up?

I plan on testing the DC offset, which I found this article on how to do it.

http://m.wikihow.com/Measure-DC-Offset

And I also plan to pop the cover and check for anything obvious like leaking caps or buldging caps.

After I do these things is there any thing else I should do before letting it rip?

Also, if you are using the receiver as your source what do you set everything to in order to check the offset?

DaveHo

For used amps, I check the DC offset & inspect the interior for any obvious signs of problems. If that all checks out I'll hook the amp to some old speakers I don't really care about for the first hour or two of use.

To check DC offset you want to turn the amp on with nothing connected to the inputs or the outputs. Let it idle for 20 minutes or so & check the offset. If it's a receiver, just select one of the analog inputs. Generally speaking if it's less than +-50mV on each channel you're good to go.

-Dave

bansheesho

Thanks for the response. I will use my rears as sacrificial testers for a couple of hours before hooking up my mains.

When you say not to hook anything to the input or output do you mean just plug it into power and turn it on? Or do you mean connect it with the interconnects but don't put it on a source that has inputs? And if the latter is the case then do you have the volume input low, medium, or high?

I am excited for my first venture into separate amp

DaveHo

Yep, just plug the power cord in & turn it on. Don't hook up speakers, don't hook up a source. One exception to this would be tube amps. You do not want to turn on a tube amp with no speakers connected. In which case, I'm not exactly sure how you check DC offset, or in the case of a tube amp if that's even a concern.